$3ij - 8j + 4k + 1 = -9j + 7k - 4$ Solve for $i$.
Solution: Combine constant terms on the right. $3ij - 8j + 4k + {1} = -9j + 7k - {4}$ $3ij - 8j + 4k = -9j + 7k - {5}$ Combine $k$ terms on the right. $3ij - 8j + {4k} = -9j + {7k} - 5$ $3ij - 8j = -9j + {3k} - 5$ Combine $j$ terms on the right. $3ij - {8j} = -{9j} + 3k - 5$ $3ij = -{j} + 3k - 5$ Isolate $i$ ${3}i{j} = -j + 3k - 5$ $i = \dfrac{ -j + 3k - 5 }{ {3j} }$